Killer immunoglobulin-like receptor repertoire on uterine natural killer cell subsets in women with recurrent spontaneous abortions

Abstract Objective The objective of this study is to investigate the distribution of inhibitory and activating killer immunoglobulin-like receptors (KIRs) on uterine natural killer (uNK) cells and the compatibility of KIR/HLA-C at the maternal–fetal interface in women with unexplained recurrent spontaneous abortion (RSA) in the Chinese population. Study design Sixteen patients with unexplained recurrent spontaneous abortion were enrolled in this study. The PCR sequence-specific primers (SSP) method was used to detect the inhibitory/activating KIRs in uterine NK cells and the HLA-C gene polymorphism expressed on the trophoblast. Results The frequencies of inhibitory KIR2DL2 in the RSA group were increased significantly compared with those of the controls. The other inhibitory KIR2DL families did not show significantly different frequencies in the RSA group. No difference in numbers of inhibitory KIR genes with statistical significance was observed between the RSA group and the controls. When analyzing activating KIRs, none of the KIR2DS1–5 family showed statistically different frequencies in the RSA group compared with the controls. Similarly, there was no statistically significant difference between the numbers of activating KIR genes in the RSA group and the controls. Finally, the matching of the inhibitory or activating KIRs/HLA combination at the maternal–fetal interface did not play a dominant role in the pathogenesis of pregnancy loss. Conclusions This study suggests that the imbalance of inhibitory and activating KIRs in uterine NKs might confer susceptibility to the occurrence of pregnancy loss. The maternal inhibitory/activating KIRs-HLA-C polymorphism expressed on trophoblast cells from decidual tissues seems to play a limited role in abortion.